Currently known minimally invasive procedures for diagnosis and treatment of medical conditions use elongate instruments, such as catheters or more rigid arms or shafts, to approach and address various tissue structures within the body. For various reasons, it is valuable to be able to determine the 3-dimensional spatial position of portions of such elongate instruments relative to other structures, such as the operating table, other instruments, or pertinent tissue structures. Conventional technologies such as electromagnetic position sensors may be utilized to measure 3-dimensional spatial position but may be limited in utility for elongate medical instrument applications due to hardware geometric constraints, electromagnetivity issues, etc. An alternative solution is the use of optical fibers containing optic shape sensors, available from suppliers such as Luna Innovations, Inc., of Blacksburg, Va., Micron Optics, Inc., of Atlanta, Ga., LxSix Photonics, Inc., of Quebec, Canada, and Ibsen Photonics A/S, of Denmark. By integrating an optical fiber into an elongate instrument such as a catheter, the real time 3-dimensional spatial shape of any or all of the length of the catheter may be determined.
Catheter structures may be designed to include an optical fiber. However, large strain changes induced by mechanical structures (such as pinching, twisting, etc.) may disrupt the accuracy of shape algorithms. The addition of components to a catheter may negatively affect the performance of a catheter (such as stiffness, inner and outer diameters, etc.).
There remains a need for apparatus and methods to improve integration and registration of a shape sensing fiber in or to an elongate instrument or other device and/or to a mechanical structure that is meaningful to the instrument or device/system.